Electric Circuts Flashcards
When was electric current discovere dand by who
Early 1700s Luigi Galvani and kater Alessandra Volta
What types of energy is in a cell
Chemical energy
What is the chemical energy inside a cell comverted into
Electical energy
Why is a conductor needed
To carry the electric cuurent from the cell to the light bulb
What is a conductor
a material or object that permits an electric current to flow easily.
What is an insulator
any of various substances that block or retard the flow of electrical or thermal currents.
What does a voltmeter mesure
Potential dufference of the battery (ability to deliver energy) in volts (V)
What does an ammeter mesure
The lectric current that flows in Ampere (A)
Series circuits
A circuit in which light bulbs are connected ina circle
Do Series or Parralel circuts glow brughter
Parralel
Advantage of parralel lights
If one bulb fuses the other bulbs still glows
Disadvantage of serues ciructs
If one bulb blows , non of the other light bublbs will shine
Which way are ammeters connected (circut wise)
Series
Which way are voltmeters connected (circut wise)
Parallel
Charge
Electric charge us an excess or defuciency of electrons
What is the size of charge determined by
Number of electrons lost or gained by an object
What quantity is charge mesured in
‘Packages’ of electrons called coulomb (C)
What is needed to obtaun electruc current
Spurce if energy (cell)
What is the function of the cell
To supply energy fo the charges which then move through the conductors and cause an electric current.The cell is the driving force for the flow of electrins htough a conductor
How can you mesure the amount of emergy transferred by the cell
By mesuring the difference in electric potential on either side of the cell.This differenec in energy is called potential difference and is meausred in (V) with the help of a voltmeter
Formula for potential difference
Energy transfered
—————————
Charge
V=W/Q
Def of a battery
Different cells which are connected to eachother
The greater the potential difference the greater the amount of…
Energy transfered to the charges
How is a current caused
The flow of charges
The amount of charge is measured in
Coulombs (C)
electric current strength is a measure of ….
how quickly the charges are flowing
How do we mesure Electric current strength
As a number of charges which flow past a point in a conductor in a certain time
Formula current strength in Ampère
Charge in Coulombs
——————————
Time
OR
I=Q/T or Q=It
The electric current in a metallic conductor is the result of…
The flow of electrons
Conventional direction of current
Although electrons are the charge carriers and move from the negatuve terminal to the posituve terminal of the battery, the current flows in the positive direction, fro, the posituve terminal to the negatuve terminal
REMEMBER-electrons flow in the opposit direction
What is electruc current meausred with
Ammeter
What does an Ammeter mesure
The amount of charge which flows through the ammeter per second
Direct current
The flow of electruc current in one direction
Alternating current
The direction of current that changes continuously
What is resistance
The force against the flow of electric current
A good conductor has a… resistance
Low resistance
A bad conductor has a… resistance
High resistance
The resistance of a conductor is a mesure of …
how difficult it is for the charges to move through the conductor
Resistance can be mesured with a…
Multimeter
What are multimeters
Instruments that can measure durect current, alternating current, potential difference and resistance
What unit in resistance mesured in
Ohm (Line bubble line)
Who was the unit for resistance named after
German scientist named George Ohm
What ar alloys
Mixtures of metals and have a high resistance
What is Nichrome
A mixture of nickel and chrome and is an alloy which is generally used as a resistor
What is the relationship between potential difference and current strength
Potential difference is directly proportional to the current strength
What can resistance be defined as
The relationship between potential difference across the ends of a conductor to the current that flows through the conductor
The resistance of a conductor can be determined by the
Gradient of the graph or by calculating the ratio V/I
What influences the resistance of a conductor
Temperature
Ohms law
The current through a conductor is directly proportional to the potential difference across the conductor at a constant temperature
Resistance =
Voltage
————
Current
What is a short circut
A commen error which occurs in circuts this happens when an extra path for the charges between 2 points in a circuit occurs
If a thick copper wire is connected across a lightbulb the lectrice current will flow through …
The copper wire and not the light bulb this is due to the fact that the copper wire offers lower rististance.The decrease in resistance in the circut leads to an increase in current and can be dangerous for the other light bulb
What do most houses have for when there are short circuts
Contact-breakers which trip the power if a short circut occurs
What does a greater potential difference mean for current strength
A greater current strength
Two light bulbs of two light bulbs offer a xxx resistance than one light bulb thus a higher resistance leads to a xxx current strength
Higher resistance that one light bulb
Leads to a weaker current strength
An increase in resistance will result in a xxx of current strength
Decrease
What deductions can we make on light bulbs (resistors) in series
- the current strength in a series circut is the same throughout the curcuit
- the potential difference is divided between resistors (V total=V1 + V2 + V3)
-the total resistance is the sum of the separate resistors (R total=R1 + R2 +R3)
What is the relationship between potential difference and current strength
Directly proportional
